Multi-functional leak detection instrument along with sensor mounting assembly and methodology utilizing the same

ABSTRACT

A leak detection instrument may comprise a housing, a gas sensor supported relative to the housing, an AE sensor for generating a sound detection input signal upon exposure to gas leakage, processing circuitry for producing output signals, and an output device. The AE sensor may include an elongated mounting member, an AE sensor housing supported by the mounting member, and an AE sensor disposed therein. Improvements to leak detection instruments, an AE sensor mounting assembly and a method of monitoring a device to ascertain leakage of a target gas therefrom are also provided.

FIELD OF THE INVENTION

The present invention broadly relates to the field of leak detection.More particularly, the present invention is concerned with detectors andmethodologies for monitoring gas leakage to detect the presence, andlocation, of selected gases, as well as the airborne sound attendanttherewith. The invention is even more specifically directed to theintegration of known sensing techniques into a single instrumentpackaging to facilitate leak detection.

BACKGROUND OF THE INVENTION

There are various situations where it is important to detect thepresence of specific gases in an atmosphere. Certain gases may beharmful to humans making it desirable to monitor a system's environmentto ensure that the concentration of selected gases does not exceedcertain threshold limits. Pressurized systems also need to be monitoredfor leaks to ensure they are functioning properly to avoid futuredamage. Leak detection, however, can be a complex and costly endeavor.Depending on the system and the application where a gas or liquid may bestored, the sensitivity of a leak detector to a given substance is acomplex function of operational, environmental, health and economicissues.

For example, air escaping out of a compressor tank or air line may bedifficult to locate and repair because the sound it makes can be maskedby other sounds or the location may be invisible or inaccessible. Otherexamples are the leakage from air conditioning equipment, fireextinguishing equipment, or refrigerant gas out of a refrigerationsystem. Where a refrigeration system is concerned, for example, thefunctional, environmental, health and economic issues are unique.Government regulations may prohibit the leakage of a refrigerant gasabove a certain level. Loss of refrigerant may be accompanied by loss oflubricant, which will affect the function of the system. Both of theseconditions alone will generate cost to the owner, which will have to actwithin constraints of the law and economic capabilities to properlymaintain the system.

Depending on the nature of the system, locating the various types ofpossible leaks may require completely different tools and methodologies.Location of a refrigerant leak may require a panoply of tools andequipment since, for a given situation, there may be a number ofrefrigerant gases each requiring a special detector. The gas familiesused in refrigeration allow the use of sensors that “cross-over”,meaning that a particular sensor optimized to work best for one gas,such as R12, will also work for another gas, such as R134A. However, ifthe gas is from a different family, such as R422, the sensor used in thedetection of R12 gas will not be as sensitive. Sensitivity of sensorsfor a particular gas or family of gases is referred to as the minimumdetectable amount (MDA) and is measured in parts per million (ppm).

Reliability of readings from gas sensors, however, can be misleadingsince the dispersion of leaking gas in air results in the density of thegas varying according to the distance the measurement is taken from theleak source. For example, suppose the ultimate sensitivity of a leakdetector is 10 ppm for a given type of gas. If the dilution of the gasin air is such that there is only 1 ppm, the detector will not detectits presence. Such a situation is possible when there is wind blowingthe leaking gas, thereby dispersing it, and in effect diluting it.Situations such as this make it very difficult to ascertain theexistence of a leak and pinpoint its location because, to trace the gasto the leak, the sensor must collect enough gas and the density of thisgas must stay within the sensor's capabilities. Even though the leakrate may be orders of magnitude over the MDA of the sensor, a wind'sdispersion effect may reduce it to below the MDA. Such a situation canbe quite common in refrigeration and A/C field servicing. Accordingly, atechnician needs to carry several leak detectors since they complimenteach other in the quest of locating a leak.

Within the family of gas sensors, also referred to as gas detectors, arethe chemical properties leak detectors (CPLDs). CPLDs are very sensitiveand can reach an MDL of 0.1 oz per year, but suffer from contamination,wind dilution and saturation. CPLDs are based on ionization or ioncapture of the leaking gas. Special sensing elements are used togenerate a signal when the gas is present. Examples of CPLDs arediscussed in the following patents: U.S. Pat. No. 5,104,513 to Lee etal., U.S. Pat. No. 5,932,176 to Yannopoulos et al., U.S. Pat. No.3,991,360 to Orth et al., and U.S. Pat. No. 4,045,729 to Loh.

Another type of gas sensor, known as the thermal conductivity detector(TCD), compares the thermal conductivity of air to a gas that is drawnby heating a wire or thermal sensor. Changes to the thermal balance ofthe wire causes the sensor to detect the presence of a gas. Sensorsusing thermal conductivity, while suffering from the same problems asthe CPLD type sensors, can detect inert gases at low levels that areundetectable by CPLDs and ultrasonic sensors. An example of acommercially available leak detection instrument which utilizes a TCD isthe LeakCheck, sold by EFD Instruments of NY. Gas sensors can also be ofa variety of other types including the Photo Ionization type (PID), suchas discussed in U.S. Pat. Nos. 5,561,344 and 6,509,562, the chemicaldetector type (CD), the laser interferometer type (LID), the coronadischarge type (CDD), microelectromechanical systems (MEMS) basedsensors, or surface acoustic wave (SAW) sensors, to name a few.

Other types of known detectors can broadly be characterized as listeningdevices because they listen to the sound caused by leak flow into or outof a system. This sound can be either air-borne or structure-borne andbe in the sonic or ultrasonic range. Listening devices of this typegenerally utilize an acoustic emissions (AE) sensor to detect the leak.One particular type of listening device is known as an ultrasonic leakdetector (ULD). There are a number of ULD instruments available, such asthose described in my following patents: U.S. Pat. No. 5,103,675, U.S.Pat. No. 5,432,755, U.S. Pat. No. 5,436,556, U.S. Pat. No. 6,058,076,U.S. Pat. No. 6,079,275, and U.S. Pat. No. 6,163,504. Each of my earlierULDs employs an AE sensor, either alone or in conjunction with a touchprobe, to conveniently detect air-borne sound, structure-borne sound, orboth.

ULDs are very useful in refrigeration systems since they can detectvacuum leaks and are not affected by wind. ULDs listen to the sound theflow of a leaking gas makes as it escapes from a container or is beingsucked in under vacuum. Sound is generated as the gas expands and itsflow becomes turbulent. Because of this principle, ULDs can detect anytype of gas. Under ideal conditions, the minimum flow ULDs can detect isapproximately 0.01 SCCM (standard cubic centimeters per minute). Theirultimate sensitivity, though, does not reach the desired leak flow rateof 0.5 oz per year in the refrigeration field. Additionally, backgroundnoise can make it difficult to locate the leak point. Thus, leakdetection with ULDs can also have its limitations.

Another approach to ascertaining the presence of gases, for examplerefrigerant gases which have been injected with a dye, is through theuse of ultraviolet (UV) illumination. This causes the gas, or itsresidue, to fluoresce, thereby leaving a visual indication of itspresence.

While the art is ripe with numerous approaches for detecting leakcharacteristics, these various techniques have essentially evolved inisolation. The result has been that service technicians often neednumerous tools at their disposal to effectively monitor leaks. This canbecome cumbersome and often results in inefficiency, inconvenience, andadded cost. Accordingly, there is a need to overcome these disadvantagesso that technicians servicing any type of appliance that is charged, forexample with a refrigerant gas, can do so reliably, in a time-efficientmanner and with fewer tools. The present invention is directed tomeeting these needs.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new and usefulleak detection instrument for monitoring gas leakage from a device.

Another object of the present invention is to provide a new and usefulmethodology for monitoring a device to ascertain leakage of a target gastherefrom.

A further object of the present invention is to provide a new and usefulacoustic emissions sensor mounting assembly for use with a scientificinstrument.

Still a further object of the present invention is to provide such aleak detection instrument that is multi-functional by integratingexisting sensor technologies.

Yet another object of the present invention is to improve upon existingleak detection instruments which utilize AE sensor technologies byincorporating gas sensor capabilities, and vice versa.

It has been found that these objectives can be met, and thedisadvantages associated with the prior art can be overcome, byintegrating known gas detection capabilities into a single instrument.Of particular interest in the present application is the integration ofat least gas sensing capabilities together with AE sensing capabilitiesinto a single instrument. However, the ordinarily skilled person wouldunderstand from the description to follow that any combination of gasdetection capabilities which has heretofore not been practiced utilizinga single leak detection instrument is specifically envisioned.

The multi-functional leak detection instrument which is the subject ofthe present application could prove very beneficial, for example, totechnicians who service any type of appliance that is charged with arefrigerant gas. The AE sensor side would be able to detect the soundgenerated by the leaking gas and pinpoint its location, while the gassensor side would be able to detect its presence.

Understandably, the particular environment for an instrument whichintegrates these technologies would be dictated, at least in part, bythe choice of gas sensor. For example, if the gas sensor is for halogengases, the combination would likely be used in refrigeration systems,whereas if the gas sensor is for combustible gases, then heating,furnace or combustion engineering, chemical and petrochemicalapplications could use the combination. Additionally, if the applicationis for Volatile Organic Compounds (VOC) the combination can be used in aspecialized chemical detection for the detection of paint thinners andthe like.

In accordance with the above, one embodiment of the present inventionconcerns an acoustic emissions (AE) sensor mounting assembly that isadapted for connection to a scientific instrument which includes aninstrument housing, processing circuitry associated with the instrumenthousing, and an output device. The AE sensor mounting assembly broadlycomprises an elongated mounting member adapted to releasably connect tothe instrument housing, an AE sensor housing supported by the mountingmember, and an AE sensor disposed within the AE sensor housing. The AEsensor, which may be a microphonic element for detecting soundsattendant with gas leakage, is adapted to be placed in electricalcommunication with the processing circuitry and operates upon exposureto sound attendant with gas leakage from a device to generate an inputsound detection signal for processing. This input sound detection signalcan then be communicated, such as through electrical interconnects, tothe instrument's processing circuitry to produce an output signal sothat perceptible output can be generated in response thereto by theoutput device.

The elongated mounting member may be a flexible tube, sometimesgenerally referred to as a “gooseneck”, having a proximal end releasablyconnected to the instrument housing and extending from the proximal endto terminate at a distal end. Preferably, the AE sensor housing isreleasably connected to the distal end of the flexible tube. Also, theAE sensor housing preferably incorporates a through bore incommunication with the tubular extension to define a gas flow passagewaybetween upstream and downstream ends of the AE sensor mounting assembly.To this end, the AE sensor housing may include a pair of bored end capsthat are joined together to substantially surround an AE sensor housinginterior. A downstream one of these end caps is removably attached tothe mounting member, with an upstream one of the end caps supporting theAE sensor.

The AE sensor, such as the microphonic element discussed above, isadvantageously mounted on a circuit board that is supported within theAE sensor housing interior. A plurality LEDs may be mounted on thiscircuit board, on the same surface as the AE sensor. The group of LEDsmay comprise ultraviolet LEDs, infrared LEDs, or visible LEDs of anyappropriate color. When UV LEDs are used, they operate upon emission ofultraviolet light to cause an appropriately dyed target fluid/gas or itsresidue in the vicinity of the AE sensor housing to fluoresce and thusbecome visible. Both the ultraviolet LEDs and the microphonic elementproject forwardly in an upstream direction. The upstream end capincludes a central bore that is directionally aligned with themicrophonic element and a plurality of regular offset bores that areeach axially aligned with a respective one of the ultraviolet LEDs. Ifdesired, photo-detectors, such as photodiodes or charged coupled devices(CCDs), could also be used in conjunction with one or more of the UVLEDs. Each photodiode or CCD would be reactive to fluorescent light fromthe target gas when it, or its residue, is exposed to UV radiation fromthe UV LEDs to generate a corresponding photo detection signal forprocessing.

A plurality of visible LEDs may be mounted on an opposite side of thecircuit board and adapted to be placed in electrical communication withthe processing circuitry. In addition a plurality of visible LEDs may bemounted in place of the UV LEDs or mixed together with them which canserve to illuminate an area in a vicinity of the AE sensor housing toaid the user in low light situations. Preferably, whatever types ofLED's are chosen, they are equiangularly distributed about the AEsensor. A light transmissive annular ring may also be sandwiched betweenthe sensor housing's end caps in radial alignment with the visible LEDs.

In a preferred exemplary form, the leak detection instrument comprises agas sensor and an AE sensor each supported relative to the instrumenthousing, with the processing circuitry operative to receive respectiveinput signals from each of these sensors and the output device operativeto produce perceptible output in response thereto. To this end, theprocessing circuitry may incorporate a microcontroller, amicroprocessor, a digital signal processor (DSP), or one or morecombinations thereof. Advantageously also, the processing circuitry canincorporate analog, digital or a combination of analog and digitalprocessing components.

The gas sensor may be a variety of types known in the art, such as achemical property leak detector (CPLD), a corona discharge detector(CDD), a thermal conductivity detector (TCD), a photo ionizationdetector (PID), a laser interferometer (LID), a microelectromechanical(MEMS) based detector, a chemical resistor sensor (CRS), or a surfaceacoustic wave (SAW) detector, to name a few. The gas sensor ispreferably disposed within the instrument housing upstream of a gas pumpwhich operates upon actuation to draw the selected gas toward the gassensor, such that when the gas sensor is exposed to the selected gas itgenerates a corresponding gas detection input signal. The AE sensor ispreferably supported at an upstream location external to the instrumenthousing within an AE sensor mounting assembly, as discussed above.Preferably also, a hydrophilic filter is interposed between the AEsensor and the gas sensor, and located within the AE sensor housing,such that the gas is drawn by the pump through the filter before cominginto contact with the gas sensor. Integrity of the filter can bemonitored using a vacuum switch so as to produce an appropriate blockedfilter indication (BFI) signal if the filter becomes contaminated or isefficacy reduced below a certain level. Preferably also, the processingcircuitry which receives the gas detection input signal and the sounddetection input signal is operative to parallel process these signalsand transmit corresponding conditioned signals to the output device.

Another embodiment of the present invention contemplates a methodologyof monitoring a device to ascertain leakage of a target gas therefrom.According to a preferred embodiment of this methodology, both a gassensor and an AE sensor are provided and each exposed to the target gasto generate a gas detection input signal and a sound detection inputsignal, respectively. These two input signals are then processed toproduce at least one output signal, and perceptible output is displayedin response thereto. Also according to this methodology, a vacuum iscreated to draw the target gas along a gas flow passageway from anupstream location that is in a vicinity of a suspected leak, through anappropriate filter, and towards a downstream location whereby the targetgas encounters the gas sensor. The methodology also may incorporate thevisible illumination of an area in the vicinity of the upstreamlocation, as well as illumination of the area with ultraviolet light tocause the target gas to fluoresce.

The present invention also relates to improvements to known leakdetection instruments, such as the ultrasonic leak detectors discussedin any of my following earlier patents, the disclosures of which areincorporated herein by reference: U.S. Pat. Nos. 5,103,675, 5,432,755and 5,436,556, 6,058,076 and 6,163,504. The leak detection instruments,such as described in any of the above patents, incorporate an AE sensorsupported relative to the instrument housing which is operative uponexposure to sound attendant with leakage from a device to produce acorresponding sound detection input signal. Processing circuitryreceives the sound detection input signal and producing an AE sensoroutput signal in response thereto. Output circuitry generates associatedAE sensor perceptible output, such as an audio or visible display, inresponse to the AE sensor output signal. The improvement to leakdetection instrument(s), such as these, broadly comprises theincorporation of a gas sensor supported relative to the instrumenthousing which is operative upon exposure to a selected gas to generate acorresponding gas detection input signal. The improvement alsopreferably incorporates a pump within the instrument housing for drawingair passed the gas sensor, and gas sensor processing circuitry inelectrical communication with the gas sensor for generating acorresponding gas detection output signal. To this end, the outputcircuitry is further operative to generate a associated gas sensorperceptible output in response to the gas detection output signal.According to this improvement, the gas sensor may be any of the varioustypes discussed above.

Yet another aspect of the present invention relates to an improvement toa leak detection instrument, such as one incorporating known gas sniffertechnology. Here, a gas sensor is supported relative to the instrumenthousing and operates upon exposure to a selected gas to generate acorresponding gas detection input signal. A pump draws air past the gassensor and output circuitry displays associated gas sensor perceptibleoutput in response to the gas detection input signal. The improvement tosuch a leak detection instrument broadly comprises the provision of anAE sensor supported relative to the instrument housing which generates acorresponding sound detection input signal upon exposure to soundattendant with leakage of the selected gas, as well as AE sensorprocessing circuitry in electrically communication with the AE sensorwhich operates in response to the sound detection input signal togenerate a corresponding sound detection output signal. The outputcircuitry is preferably further operative in response to the sounddetection output signal to generate associated perceptible output.

These and other objects of the present invention will become morereadily appreciated and understood from a consideration of the followingdetailed description of the exemplary embodiments of the presentinvention when taken together with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment for the leakdetection instrument of the present invention;

FIG. 2 is a first exploded perspective view of the leak detectioninstrument of FIG. 1;

FIG. 3 is a second exploded perspective view of the leak detectioninstrument of FIG. 1;

FIG. 4 is a side view in partial cross-section of the leak detector'sacoustic emissions (AE) sensor mounting assembly;

FIG. 5 is an enlarged side view in elevation of the housing assembly forthe AE sensor mounting assembly;

FIGS. 6(a) and 6(b) are each exploded perspective views of the AE sensorhousing assembly;

FIG. 7(a) is a rear plan view of the downstream end cap for the AEsensor housing;

FIG. 7(b) is a front plan view of the downstream end cap for the AEsensor housing;

FIG. 8(a) is a front plan view of the upstream end cap for the AE sensorhousing;

FIG. 8(b) is a rear plan view of the upstream end cap for the AE sensorhousing;

FIGS. 9(a) and 9(b) are each exploded perspective views for illustratingthe AE sensor housing's circuit board assembly;

FIG. 10 is a rear plan view of the sensor housing's annular ring;

FIG. 11 is a cross-section of the annular ring as viewed about line11-11 in FIG. 10;

FIG. 12 is a block diagram illustrating, for the most part, theprinciple features associated with known instruments which employ aselected type of gas sensor for gas detection;

FIG. 13 is a block diagram showing principle components of a gas sensorblock which may be incorporated into a leak detection instrumentaccording to the present invention;

FIG. 14(a) illustrates, in block diagram form, principle aspects of amulti-functional leak detection instrument according to one embodimentof the present invention which incorporates analog processing circuitry;

FIG. 14(b) illustrates, in block diagram form, principle aspects of amulti-functional leak detection instrument according to anotherembodiment of the present invention which incorporates both analog anddigital signal processing;

FIG. 14(c) illustrates, in block diagram form, principle aspects of amulti-functional leak detection instrument according to yet anotherembodiment of the present invention which incorporates analog anddigital signal processing, as well as a digital signal processor (DSP);

FIG. 15(a) is a perspective view of a second exemplary embodiment for anAE sensor housing of the present invention;

FIG. 15(b) is an exploded perspective view of the AE sensor housing ofFIG. 15(a);

FIG. 16(a) is a perspective view of a third exemplary embodiment for anAE sensor housing of the present invention;

FIG. 16(b) is an exploded perspective view of the AE sensor housing ofFIG. 16(a);

FIG. 17(a) is a front plan view of one of the end caps for the AE sensorhousing shown in FIGS. 16(a) and 16(b);

FIG. 17(b) is a rear plan view of the end cap of FIG. 17(a);

FIG. 18(a) is a perspective view of a fourth exemplary embodiment for anAE sensor housing of the present invention;

FIG. 18(b) is an exploded perspective view of the AE sensor housing ofFIG. 18(a);

FIG. 19(a) is a perspective view of a fifth exemplary embodiment for anAE sensor housing of the present invention;

FIG. 19(b) is an exploded perspective view of the AE sensor housing ofFIG. 19(a);

FIG. 20(a) is a perspective view of a sixth exemplary embodiment for anAE sensor housing of the present invention; and

FIG. 20(b) is an exploded perspective view of the AE sensor housing ofFIG. 20(a);

FIG. 21 is a perspective view of a sixth exemplary embodiment for an AEsensor housing of the present invention;

FIG. 22 is a rear plan view of the AE sensor housing of FIG. 21;

FIGS. 23(a) and 23(b) are exploded perspective views of the AE sensorhousing shown in FIG. 21;

FIG. 24 is a perspective view of another exemplary embodiment for adetection instrument of the present invention, and showing it in use todetect the presence of a gaseous substance, or it's residue, on aconduit;

FIG. 25 is a perspective view of the detection instrument shown in FIG.24; and

FIG. 26 is a perspective view of yet another exemplary embodiment for adetection instrument according to the present invention, and showing itin use to detect the presence of a gaseous substance, or it's residue,on a conduit.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present invention concerns instruments for detecting leakage of gasor liquid from a device. For purposes of the disclosure, it should beappreciated that the term “device” should be construed as broadly aspossible to encompass any kind of machinery, equipment, system or thelike wherein a gas or liquid may be found and for which it is desirableto trace or ascertain the existence of leakage therefrom. Those familiarwith servicing such devices would recognize that a panoply of tools andequipment may be required to locate leaks of different types andcharacteristics. Accordingly, the present invention relates to anintegrated leak detection instrument which incorporates two or moreknown technologies to provide a versatile tool for service repairtechnicians and the like. To this end, while the exemplary embodiment ofthe present invention is discussed in connection with a singleinstrument which incorporates gas sensor technology and AE sensortechnology, the present further contemplates instrumentation andmethodologies which incorporate other combinations of detectiontechniques into a single instrument package.

With initial reference then to FIGS. 1 and 2, an exemplary embodiment ofa leak detection instrument 10 of the present invention is shown. Leakdetection instrument 10 is capable of detecting various characteristicsassociated with leakage from a device. Leak detection instrument 10 hasan instrument housing 12 which internally supports appropriateprocessing circuitry that may be mounted on independent, yetinterconnected, circuit boards. As will be discussed in greater detailbelow, leak detection instrument 10 in its preferred embodimentincorporates a plurality of sensors, namely an acoustic emissions (AE)sensor and a gas sensor.

Preferably also, leak detection instrument 10 is provided with bothvisible and ultraviolet LEDs to facilitate the leak detection process.Housing 12 also supports a signal strength indicating meter 14, whichmay be an array of light emitting diodes for visually indicating thestrength of the received input signals from either or both of the AEsensor and the gas sensor. Another visual output in the form of analphanumeric display 16 indicates signal strength of the receivedsignals from the sensors, as well as displaying the various modes ofoperation and the volume and sensitivity levels for detector 10. Audibleoutput is obtained by way of earphones (not shown) which areelectrically connected to the circuitry contained within housing 12 viaheadphone jack 18. A first push button activation switch 20 is providedto toggle leak detection instrument 10 between on and off conditions. Asecond push button activation switch 22 may be provided to togglebetween the various operational modes for the leak detection instrument,and third and fourth push button activation switches 24 and 26 may beused to selectively adjust the sensitivity and volume levels within agiven operational mode.

The various circuitry components associated with the processing of sounddetection input signals generated by the AE sensor associated with theleak detection instrument 10 can take on a variety of forms andcharacteristics. For example, analog processing circuitry is discussedin my U.S. Pat. Nos. 5,103,675, 5,432,755 and 5,436,556, while acombination of analog and digital processing is disclosed in my U.S.Pat. Nos. 6,058,076 and 6,163,504. As discussed below with reference toFIGS. 12-14(c), relevant portions of each of these above patents,pertaining to processing signals from the AE sensor of leak detectioninstrument 10, are incorporated herein by reference. It should also beunderstood that the housing 12 for the leak detector could assume avariety of different looks and configurations such that the figures arefor illustrative purposes only. Indeed, the configuration of theinstrument's housing need only be designed to accommodate the variouscomponents necessary for effectuating the purposes of the presentinvention, with the various audible and visual output indicators,selection switches and the like being tailored to one's designpreferences.

As perhaps best shown in FIG. 3, the instrument housing 12 for leakdetection instrument 10 includes a pair of upper and lower case pieces11 and 13, respectively, which substantially enclose an instrumenthousing interior 15 that is divided into a battery compartment region 17and a circuit board(s) region 19. As also generally shown in FIG. 3, agas sensor 30 and an associated pump 40 are appropriately supportedwithin the interior 15 of housing 12. Together, sensor 30 and pump 40can be considered a gas sniffer. Power to gas sensor 30 and pump 40 isprovided via appropriate electrical leads 32, 34 and 42, 44. These leadscouple to the detector's power supply, i.e. battery, via appropriatepower supply regulator circuitry, as would be apparent to the ordinarilyskilled artisan in this field. To this end gas sensor 30 may be achemical properties leak detector (CPLD) such as that described in U.S.Pat. No. 5,932,176 to Yannopoulos et al., issued Aug. 3, 1999. In thispatent, the disclosure of which is incorporated by reference, a halogengas sensor and its associated electrical circuitry is described for usein detecting refrigerant vapors.

Preferably, pump 40 is located downstream and in general directionalalignment with gas sensor 30 so that the vacuum created by pump 40serves to draw environmental gas in a downstream direction from avicinity of the upstream end 9 of leak detection instrument 10, therebyto encounter gas sensor 30. As also generally shown in FIG. 3, housing12 may be provided with an appropriate gas purge port 45 formed throughlower casing piece 11, or elsewhere, to evacuate the gas after it hasbeen drawn into the instrument and exposed to the gas sensor 30. Theleak detector's onboard pump 40 which draws the atmospheric gas into theinstrument's housing can be a diaphragm pump, a paddle wheel pump, avane or any other small pump. Such pumps are commercially readilyavailable from many sources worldwide, such as Thomas Industries, Inc.of Sheboygan, Wis. While a preferred gas sensor 30 for leak detectioninstrument 10 is a CPLD-type sensor such as described in the Yannopouloset al. reference, other known CPLD sensors could be substituted.Additionally, sensor 30 could be of other appropriate types withoutdeparting from the inventive concepts herein, including a TCD, a CD, aCDD a PID, a MEMS, a SAW, a CR, or an LID, to name a few. Combinationsof two or more different types of gas sensors are also contemplated.

Also associated with leak detection instrument 10 is an acousticemissions (AE) sensor mounting assembly 50 which, as shown in FIGS. 1and 2, removably attaches to the front end (i.e. base support) 13 of theinstrument's housing 12. As more particularly shown in FIGS. 2 and 4, AEsensor mounting assembly 50 includes an elongated mounting member 60which extends between a proximal end 62 having associated threads 64which threadedly engage a threaded opening 15 formed in base support 13,to a distal end 66 which supports an AE sensor housing 70, also througha threaded engagement. Mounting member 60 is preferably constructed as aflexible tube, sometimes generally referred to in the art as a“gooseneck”, to allow positioning of the AE sensor housing 70 close toareas that are difficult to reach. As such, mounting member 60 may beany appropriate construction, such as corrugated metal hose encased inan outer plastic sheath (not shown). Elongated mounting member 60, thus,has an outer sidewall 68 which surrounds an interior 65 between proximalend 62 and distal end 66.

The AE sensor housing which contains the internal AE sensor is bestshown in FIGS. 5, 6(a) and 6(b). AE sensor-housing 70 includes a pair ofbored end caps 72 and 74 which are joined together to substantiallysurround an AE sensor housing interior. Preferably sandwiched betweenend caps 72 and 74 is an annular ring 76 made of an optically clearmaterial, such as a red transparent plastic. As can be seen in thefigures, AE sensor housing 70 has a tapered nose construction by virtueof the configuration of end caps 72 and 74. That is, the distal upstreamend cap 74 has a cylindrical base portion 75 and a frustoconical portion77. Similarly, downstream end cap 72 which threadedly engages thetubular mounting member 60 has a cylindrical base portion 71 and afrustoconical portion 73. Cylindrical base portions 71 and 75 aremounted in facing relationship to one another so that the AE sensorhousing 70 generally tapers in both the upstream and downstreamdirections. Housed internally within the AE sensor housing 70 is ahydrophilic filter element 80 and a circuit board assembly 90 whichincludes a circuit board substrate 92 having a plurality of surfacemounted electrical components including the AE sensor 94.

End caps 72 and 74, which may be constructed of plastic or othersuitable material, are secured together by a plurality of screws 79 eachof which extends through respective aligned bores 52, 54, 56 that arerespectively formed through end cap 72, annular ring 76, and circuitboard 90, and threaded cavities 58 formed partially through end cap 74.The bores 52 for end cap 72 may best be seen in FIGS. 7(a) and 7(b),whiles the cavities 58 for end cap 74 may best be seen in FIG. 8(b). Asshown in the various figures, each piece 72, 74, 76 and 92 has threesuch bores/cavities which are equiangularly distributed about theircenters.

Circuit board assembly 90 will now be generally discussed with referenceto FIGS. 9(a) and 9(b). Circuit board assembly 90 includes a disk-shapedprinted wire circuit board substrate 92 to which is surface mounted avariety of electrical components which comprise the front end processingfor the AE sensor side of the leak detector, as well as providing bothvisible and ultraviolet (UV) illumination capabilities. Moreparticularly, AE sensor 94 is mounted and projects from an upstream face95 of substrate 92, as do a plurality of UV LEDs 91 which areequiangularly distributed around AE sensor 94. If desired, photodiode(s)or CCD(s) could be incorporated to work in conjunction with one or moreUV LEDs 91 shown in the various figures. These photodiode(s)/CCD(s)would understandably react to the receipt of fluorescent light from thetarget gas, or its residue, to generate or more corresponding diode orCCD detection signals, thereby providing UV sensing capabilities. Asalso shown in FIGS. 9(a) and 9(b), a plurality of visible LEDs 93 aresurface mounted to a downstream face 96 of substrate 92 andequiangularly distributed about the center thereof. These visible LEDs93 may be in general radial alignment with the UV LEDs.

An IC chip 97 is also surface mounted to downstream face 96. IC chip 97provides pre-amplification for the input sound detection signal producedby AE sensor 94. IC chip 97 specifically houses one or more amplifiers,such as amplifier 106 associated with the pre-amplification circuitry 34that is discussed with reference to FIGS. 2 and 3(a) of my U.S. Pat. No.6,058,076, the disclosure of which is incorporated herein by reference.Although not shown in FIGS. 9(a) and 9(b) here, other discrete biasingcomponents, such as those specifically shown in FIG. 3(a) of the '076patent for appropriately biasing amplifier 106, are preferably alsosurface mounted to substrate 92. As such, IC chip 97 and its associatedcomponents, accomplishes some of the front end processing functions forAE sensor 94. In addition, the respective anodes and cathodes of UV LEDs91 and visible LEDs 93 are electrically connected to appropriate pads inthe circuit board 92, to provide them with power.

As generally represented in FIGS. 5, 6(a) and 6(b), a pluralityelectrical leads 87, contained in an insulative sleeve 89, extend fromsubstrate 92 centrally through the bored sensor housing assembly 70. Tothis end, each of annular ring 76, hydrophilic filter 80 and downstreamend cap 72 are centrally bored to accommodate the electrical leads.Filter element 80, in fact, has a radial slot 82 which communicates withits central bore 84 to provide for easy insertion of the electricalleads. Although not specifically shown, it should be appreciated thatthese leads 87 also extend down through the interior 65 of elongatedmounting member 60 to appropriately connect to the remainder of theprocessing circuitry contained on the circuit boards internallyassociated with the housing for the leak detector of the presentinvention. Many such electrical leads can be provided forinterconnection to substrate 92 to provide appropriate power and controlfor the circuitry components mounted thereon. For example, aside from agrounding wire, control inputs would be provided for each set ofUV-LEDs, visible LEDs, photodiodes and CCDs, if any. In addition, whereonly one amplification stage is employed, two electrical leads wouldprovide power to the amplifier, with another lead providing theamplified signal output from the AE sensor 94. Alternatively, wheremultiple amplification stages are provided, differential output can beobtained, thus requiring one additional lead for the differentialoutput.

When the AE sensor housing 70 is in the assembled state shown in FIG. 5,the upstream face 95 of substrate 92 is seated between the annular wall46 of end cap 74 (FIGS. 6(b) and 8(b)) and the annular wall 71 of ring76 (FIGS. 6(a) and 11) such that the AE sensor 94 is received within thebored central opening 42 of end cap 74 proximate to lip 44 thereof. Assuch, AE sensor 94 is directionally exposed to the external environmentso that it can detect the sound attendant with leakage in the vicinityof the upstream end of the AE sensor head and generate a correspondingsound detection input signal which is conditioned and transmitted viathe electrical leads to the remaining processing circuitry disposedwithin the leak detector's housing. The projecting brim wall 47 of endcap 72 (FIGS. 6(a) and 7(b)), when in the assembled state, is mounted infacing contact with annular wall 77 of ring 76. The visible LEDs 93 arepositioned in general radial alignment with angled internal wall 79 ofannular ring 76. This angled wall 79 is beveled at an angle so that thelight emitted from the visible LEDs 93, is reflected toward the outsidering wall creating a radial external halo effect around sensor housing70 to indicate the presence of an output signal from the sensors, suchas in the case of a detected leak. Understandably, the particular angleof beveled wall 79 which accomplishes this halo effect is dependent uponthe material selected for annular ring 76 and the directionalorientation of the visible LEDs 93 which, in the illustrated embodiment,are surface mounted to emit light in the downstream direction of arrow“A” in FIG. 6(b).

When the leak detector's internal pump 40 is activated it operates todraw environmental gas in a downstream direction through an airflowpassageway defined by the construction of the AE sensor head 70 and thetubular mounting member 60 so that the environmental gas encountersinternal gas sensor 30. To this end, a plurality of equiangularlydistributed air ports are bored through the various pieces of the AEsensor housing assembly to permit the passage of airflow therethrough.More particularly, three such equiangularly distributed apertures 41 areformed through upstream end cap 72 (See FIGS. 5, 6(a), 6(b), 8(a) and8(b)). These apertures 41 are aligned with respective apertures 43formed through the circuit board substrate 92. Thereafter, the drawn gaspasses through opening 75 in annular ring 76, through hydrophilic filter80, centrally through end cap 72 and down the interior 65 of mountingmember 60. A gas flow passageway is, thus, defined for the AE sensormounting assembly.

As discussed above, the exemplary embodiment of the leak detector of thepresent invention merges existing leak detection technologies into asingle instrument package such that its various versatilities can bereadily appreciated. That is, leak detection instrument 10 is capable ofdetecting the sound attendant with leakage by virtue of the AE sensor 94that is supported relative to the instrument housing which generates acorresponding sound detection input signal for processing. Additionally,the internal gas sensor 30 is operative upon exposure to a target gas,by virtue of it being drawn to the gas sensor by the internal pump 40,to generate a corresponding gas detection input signal for processing.Activation of the ultraviolet LEDs 91, which emit UV radiation throughthe aligned apertures 59 formed in end cap 74 (FIGS. 8(a) and 8(b)),causes an appropriately dyed target gas which is in a vicinity of the AEsensor housing 70 to fluoresce, thereby providing an alternativeindication of presence of a target gas. Finally, activation of thevisible LEDs 93 indicate the location of a leak informing the operatorin such a way that he does not have to shift his eyes from the suspectedleak point to observe the various visual outputs on the housing of theinstrument.

Having described the structural components which comprise the leakdetection instrument 10 according to the exemplary embodiment of thepresent invention, the principal features of the electronic circuitryfor accomplishing these various integrated detection capabilities willbe discussed with reference to the block diagrams of FIGS. 12-14(c).However, the ordinarily skilled artisan familiar with the pertinentprior art, as it relates to gas sensor technologies, should recognizethat numerous teachings exist for separately detecting variouscharacteristics of gases, or families of gases, as well as theprocessing of detection signals attendant therewith. The same holds truefor AE sensing technologies. Accordingly, the integration of thesesensing technologies and their processing into a single instrumentpackage, albeit heretofore unrecognized in the art, need only bediscussed diagrammatically to be enabling to the ordinarily skilledartisan.

With this in mind, initial reference is made to the block diagram ofFIG. 12 which, for the most part, illustrates the principal featuresassociated with known gas detection instruments which incorporate a gassensor. Representative gas detection instrument 100 includes a selectedgas sensing element 101, which can be of any appropriate type for use indetecting particular gases or particular families of gases. To this endthe selected gas sensing element 101 can, for example, be a coilconstruction such as described in U.S. Pat. No. 5,932,176 to Yannopouloswhich is reactive to the presence of halogen gases. Sensing element 101is powered by an appropriate bias voltage power supply 102 and is heatedby a heater 103 which has its own power supply 104. A gas sensor 105 is,thus, comprised of those components which make up blocks 101-104, andthis gas sensor is used in a gas detection instrument 100 which includesadditional processing circuitry components as diagrammatically shown inFIG. 12.

An orifice 106 is provided through the instrument's housing so thatatmospheric gas is communicated to the selected gas sensing element 101.The atmospheric gas passes through a filter element 107 that isinterposed between orifice 106 and sensor 101. The atmospheric gas isdrawn past sensing element 101 by a vacuum pump 108 and then exhaustedto the atmosphere in any appropriate manner as shown by block 109. Thesignal generated by the gas sensor 105 is passed to front-end processingcircuitry 110 which may include a signal pre-amplifier 111, sensitivityadjustment circuitry 112 and signal amplifier 113. After passing throughprocessing block 110, the conditioned gas detection signal is then sentto output circuitry 115 to provide either visual or audible output to auser. For visual output, the conditioned signal 114 is passed through asignal level detector 116 and then to an appropriate signal intensitydisplay 117 which can be an array of LEDs, a numeric display or thelike. Conditioned signal 114 also passes through a threshold gate 118controlled by an appropriate threshold setting 119 and is then passed toa speaker element, such as a beeper 120 to provide the audio output. Atone control signal 121 may also be passed to the beeper 120 from thesignal level detector 116 so that intensity of the detected gas isindicated to the user via different tonal outputs.

At this point, the gas detection instrument 100 corresponds to thoseknown in the art. However, two additional features can be provided forinstrumentation 100 which it is believed are not known in the art. Theseinclude a vacuum/pressure sensor 122 and a block filter indicator (BFI)123 which are each associated with filter element 107. Vacuum/pressuresensor 122 acts as a switch that produces a blocked filter indicatorsignal when the filter element 107 becomes contaminated and its efficacyreduced below a selected threshold which can be set to one's preference.This BFI signal can then be processed by the processing circuitry foradjustments and alarms as desired. While utilization of vacuum/pressuresensing devices in connection with filter elements is known, it is notbelieved that this has been incorporated in existing gas detectioninstruments.

With reference now to FIG. 13, it may be appreciated that a gas sensorblock 125 may be defined as those components of a typical gas detectioninstrument, such as that shown in FIG. 12, which comprise the selectedgas sensor and its front end processing, but not the outputs. Dependingon the particular type of gas sensor employed, it may or may notincorporate the heater 103 and its associated power supply 104. As such,gas sensor block 125 as represented by the dashed line in FIG. 13 mayoptionally include or exclude these components depending on the sensortype. For example, heating components would be employed for a chemicalproperties leak detector (CPLD), but not for a photo ionization detector(PID). Regardless of the particular type of sensor block(s) employed, itcan be characterized as having a first output 126 as represented by node“A” in FIG. 13 which corresponds to a level, in ppm, of the conditionedgas detection input signal produced by the front end processingcircuitry, as well as a second output 127 as represented by node “B”which corresponds to the block filter indicator (BFI) signal.

FIG. 14(a) thus diagrammatically represents principle aspects of a leakdetection instrument 130 contemplated by the present invention whichonly utilizes analog processing circuitry. Detection instrument 130includes an acoustic emissions (AE) sensor block 131 and at least onegas sensor block 132. AE block 131 transmits to analog processingcircuitry 134 a conditioned ultrasonic signal 133. Conditionedultrasonic signal 133 preferably corresponds to the input signal 32produced at the output of the amplification and filter circuitry 22 asshown and discussed with reference to FIG. 2 of my earlier U.S. Pat. No.4,432,755, issued Jul. 11, 1995, the disclosure of which is incorporatedby reference. Analog processing circuitry 134 processes both theconditioned ultrasonic signal 133 from AE block 131, as well as thesignals 126 and 127 from the gas sensor block 132 in order to generateone or more outputs 135 which can be any appropriate combination ofvisual and audible indicators. The ordinarily skilled artisan should,thus, appreciate that the analog processing circuitry generallyrepresented as block 134 in FIG. 14(a), in addition to incorporatingthose features discussed in FIG. 12 with reference to the gas sensor,incorporates processing features such as those discussed in my earlier'755 patent. In the alternative, the ultrasonic portion of the analogprocessing could be accomplished as discussed in either of my earlierU.S. Pat. No. 5,103,675 or U.S. Pat. No. 5,436,556.

FIG. 14(b) diagrammatically illustrates principle aspects of a leakdetection instrument 140 which also incorporates an AE block 131 withassociated conditioned ultrasonic signal 133, as well as one or more gassensor blocks 132, each generating an appropriate conditioned gasdetection input signal 126 and a BFI signal 127. Here, however, leakdetection instrument 140 incorporates a combination of both analog anddigital processing circuitry 145 which incorporates a digital volumecontrol 146 and which is responsive to user input 147 to produce one ormore outputs, such as audible output 148, vibrational output 149 orvisual output 150. User input 147 might entail, for example sensitivitysettings for each of the sensors, threshold limits, alarm points, avolume level for the audio output, dimming level for the visual displaysand, in general, control of the instrument features. The analog/digitalprocessing circuitry 145 in FIG. 14(b) can particularly incorporatedigital processing circuitry for the AE block as discussed in my earlierU.S. Pat. No. 6,058,076 or U.S. Pat. No. 6,163,504, each of which isincorporated by reference. Optionally also, detection instrument 140 mayprovide UV illumination via UV lights 151, having power thereto providedby an associated UV light power supply 152 which forms part of theanalog/digital processing circuitry 145. Finally, FIG. 14(c)illustrates, in block diagram form, principle aspects of a thirdrepresentative embodiment of a multi-functional leak detectioninstrument 160 which is particularly adapted to receive a plurality ofsensor inputs from an acoustic emissions (AE) block 131 and a pluralityof different types of gas sensor blocks, such as a thermal conductivitydetector (TCD) block 161, a photo ionization detector (PID) block 162, achemical properties detector (CPD) block 163 and a corona dischargedetector (CDD) block 164, to name a few representative ones. As shown inFIG. 14(c), each of these gas sensor blocks 161-164 generates anassociated signal indicating a level (preferably in ppm) of therespective conditioned gas detection signal, as well as an associatedBFI signal. A suitable multiplexer 165 receives as input each of thesesignals from the gas sensor blocks, as well as the conditionedultrasonic signal 133 from the AE block 131. Multiplexer 165 outputs toan analog to digital converter (ADC) 166 which provides its input toprocessing circuitry 167. As before, user input 147 can be provided andvarious outputs 148-151 can be provided. Here, however, the processingcircuitry 167, in addition to suitable analog circuitry and amicro-controller for achieving digital control and processing, mayemploy an integrated digital signal processor (DSP). The DSP providesvarious capabilities, as would be recognized by those skilled in theart, including digital volume control and digital to analog conversion(DAC) for the received waveforms, as well as waveform reconstruction andgeneration. This functionality can be used to provide any of a varietyof control capabilities to the various outputs. In addition, as alsoshown in FIG. 14(c) the UV light power supply 152 may be eitherindependent or under control of the DSP.

Since the present invention relates to the integration of a variety oftwo or more detection technologies (e.g. AE, gas, UV) into a singleinstrument, various alternative sensor housings that are specificallyenvisioned, and which may be used as part of a multi-functional leakdetector, will now be briefly discussed with reference to FIGS.15(a)-20(b). Turning initially to FIGS. 15(a) and 15(b), an alternativeAE sensor housing 170 is shown which is identical to that describedabove with reference to FIGS. 5 and 6, except that it does notincorporate the visible LEDs. As such, AE sensor housing 170, as abovein the exemplary embodiment, includes a pair of end caps 172 and 174which are attached by appropriate threaded fasteners 179, a hydrophilicfilter 180 and a circuit board assembly 190. It should be appreciated,though, since the downstream face 195 of the circuit board assembly'ssubstrate 192 does not have surface mounted visible LEDs, the AE sensorhousing 170 similarly does not incorporate the optically clear annularring so that, here, the end caps 172 and 174 are in abuttingrelationship to one another when the AE sensor housing 170 is in theassembled state shown in FIG. 15(a).

In FIGS. 16(a) and 16(b), an AE sensor housing 270 is shown whichincorporates visible LEDs, but not UV LEDs. AE sensor housing 270, thus,includes end caps 272 and 274 which are mounted by threaded fasteners279, and a hydrophilic filter 280. However, the circuit board assembly290, while having an onboard AE sensor 294, does not have any UV LEDssurface mounted to its substrate 292, such that there is no need for theprovision of UV alignment bores formed through upstream end cap 274. Assuch, end cap 274 as shown in FIGS. 16(a), 16(b), 17(a) and 17(b)includes air passageway bores 241 and threaded bores 258 for the faster279, but no UV LED apertures through its frustoconical portion 277.

Still, another embodiment for an AE sensor housing 370 is shown in FIGS.18(a) and 18(b). Here AE sensor housing 370 is not intended for use witha leak detection instrument that incorporates a gas sensor. Rather, AEsensor housing 370 provides ultrasonic detection capabilities, UVillumination capabilities and visible light illumination capabilities.To this end, it incorporates a pair of end caps 372 and 374 which arethreadedly attached by fasteners 379, an annular ring 376 and a circuitboard assembly 390. End cap 372 and annular ring 376 are constructed asdiscussed above with reference to the exemplary embodiment of the leakdetector of the present invention. However, since there are no gasdetection capabilities in the embodiment of FIGS. 18(a) and 18(b), thereis no corresponding filter element, and there are no air passagewaybores formed through either the circuit board assembly's substrate 392or upstream end cap 374.

Yet another alternative embodiment for an AE sensor housing 470 is shownin FIGS. 19(a) and 19(b). Here, AE sensor housing 470 incorporatesultrasonic detection capabilities and visible light emissionscapabilities, but is not adapted for use with a leak detector whichincorporates gas detection capabilities or UV illumination capabilities.As such, there are no UV LEDs mounted to substrate 492 and there are nocorrespondingly aligned UV LED ports formed in upstream end cap 474.Similarly, there are no air passageway ports formed through eitherupstream end cap 474 or the circuit board assembly's substrate 492.

Another alternative embodiment for an AE sensor housing 570 is shown inFIGS. 20(a) and 20(b). Here, AE sensor housing 570 has ultrasonicdetection capabilities and UV emission capabilities, but does not havevisible light emitting capabilities and is not adapted for use with aleak detector which incorporates a gas sensor. As such, AE sensorhousing 570 does not have any surface mounted visible LEDs on substrate592, and there is no annular ring interposed between end caps 572 and574, or an internal filter element. In addition, there are no airpassageway ports formed through either the circuit board assembly'ssubstrate 592 or upstream end cap 574.

FIGS. 21-23(b) illustrate a final alternative embodiment for an AEsensor housing 670. Here, it may be seen that AE sensor housing 670accommodates both a pair of AE sensors 694 and 694′, as well as a gassensor 630. Accordingly, it may be appreciated that this embodimentcontemplates not only the provision of a plurality of sound sensors, butthe provision of a gas sensor disposed in the sensor housing so that itis not necessary to place the gas sensor within the instrument housingas shown in previous figures. In addition, while sensor housing 670would be used with a detection instrument incorporating an onboard pumpas discussed above, the ordinarily skilled artisan would appreciate thatlocation of the pump could likewise be located in the sensor housing670, if desired.

As shown, AE sensor 694 and 694′ are mounted to an elongated, generallyoval circuit board 692 in such a manner that they are aligned so thattheir axes intersect the axis of the gas sensor. Also mounted on theupstream surface of circuit board 692, between AE sensors 694 and 694′,is a socket that includes pins 679 for the gas sensor 675. Socket 675 isfastened to a support 685 that is disposed on the downstream face ofcircuit board 692. Socket 675 and support 685 are attached by fasteningelements 679′. Socket 675 accommodates gas sensor 630 so that the gassensor 630 is positioned centrally between and forwardly of the AEsensors. Support 685 is sized and adapted to accommodate an appropriategooseneck extension as shown in earlier figures.

As best shown in FIG. 23(b), a nose cone 676, which includes acylindrical portion 677 and a frustoconical portion 679, is positionedon socket 675 by aligning its diametrically opposed slots with thediametrically opposed prongs which protrude from socket 675. As alsoshown FIG. 23(b), a hydrophilic filter 680 is received withincylindrical piece 677 upstream of gas sensor 630. Left and right housingpieces 672 and 674, respectively, are configured to attach to oneanother by any appropriate means and accommodate the circuit boardsub-assembly once the various components are mounted directly orindirectly thereto.

It may be seen in the exploded perspective views of FIGS. 23(a) and23(b) that the various centrally aligned pieces associated with AEsensor housing 670 are ported members to create a gas flow passagewaythrough the housing 670, and this passageway necessarily communicateswith the gooseneck attachment when mounted thereto. In addition, as alsodiscussed above with reference to earlier figures, these ported membersaccommodate the necessary wiring (not shown) for the various circuitrycomponents so that electrical signals can be transmitted from the sensorhousing 670 to the instrument housing. Desirable front end processing,such as pre-amplification of the signals generated by the AE sensors 694and 694′, as well as possibly the gas sensor 630, can be accomplished byvarious IC chips surface mounted to the downstream facing surface ofcircuit board 692, as generally illustrated in FIG. 23(b).

With the above discussion in mind relating to the leak detector of thepresent invention, and its various alternative embodiments, it should bereadily appreciated that the present invention also contemplates amethod of monitoring a device to ascertain leakage of a target gastherefrom. This method broadly comprises the provision of a gas sensorand an AE sensor as discussed above. The gas sensor is exposed to thetarget gas to generate a gas detection input signal, and the AE sensoris exposed to airborne sound attendant with leakage of the target gas togenerate a sound detection input signal. Both signals are processed toproduce at least one output in response thereto, and perceptible outputis displayed in response to the output signal. Preferably, the sounddetection input signal generated by the AE sensor and the gas detectioninput signal generated by the gas sensor are parallel processed.Further, the methodology also contemplates the creation of a vacuum todraw the target gas along an gas flow passageway from an upstreamlocation that is in a vicinity of a suspected leak, preferably through ahydrophilic filter, and towards a downstream location whereby the targetgas encounters the gas sensor. The method also contemplates visiblyilluminating an area in the vicinity of the upstream location and/orilluminating the area with ultraviolet light thereby to cause thesubstance to fluoresce.

As discussed above, the integration of various types and combinations ofsensors into a single instrumentation are envisioned, aside from the AEsensor and gas sensor combination which is the subject of the claims ofthe present application. The remaining figures are provided to visuallyillustrate at least two other types of detection instruments which arespecifically contemplated. A first such type is shown in FIGS. 24 and25. Here, detection instrument 710 is particularly suited for detectingthe presence of a gas or its residue. To this end, one representativeenvironment for using instrument 710 is shown in FIG. 24 where a gaseoussubstance 711, or its residue, is found on a tubular conduit 713.

Detection instrument 710 generally incorporates a housing 712 whichsupports a visual display 714 for providing suitable visual outputpertaining to characteristics of the received detection signals. Audibleoutput is obtained by way of earphones (not shown) which areelectrically connected to the housing's internal circuitry via headphonejack 718. A plurality of push button switches 720 are provided to turnthe unit on and off, as well as providing various modes of operation andselective adjustment of sensitivity levels, volume, etc. The variousdesign capabilities and unit configurations would be within the purviewof the ordinarily skilled artisan.

To detect the gaseous substance 711, detector 710 may support aplurality of emitters and detectors situated symmetrically about thefront end 715. These are represented in FIG. 25. Left and rightemitters, in the form of UV LEDs 791 and 791′ irradiate the target tube713 with UV radiation as represented by emission waves 786 shown in FIG.24. This causes the gaseous substance 711 to fluoresce and generatereflection waves 788 which can be detected by left and right detectors,such photodiodes 793 and 793′, respectively CCDs could also be used fordetection as opposed to, or in conjunction with the photodiodes.Optionally, a centrally disposed gas sensor 730 may also be provided.Gas sensor 730 can be of the various types discussed above whichoperates alone, or in conjunction with an onboard pump, to create a gassniffer.

FIG. 26 illustrates an alternative construction for a detectioninstrument similar to that of FIGS. 24 & 25. Here, a sensor housing 870is supported relative to an instrument housing 812 by an extensionmember 850 so that the UV LEDs and photodiodes/CCDs are displaced fromthe optional gas sensor.

Accordingly, the present invention has been described with some degreeof particularity directed to the exemplary embodiments of the presentinvention. It should be appreciated, though, that the present inventionis defined by the following claims construed in light of the prior artso that modifications or changes may be made to the exemplaryembodiments of the present invention without departing from theinventive concepts contained herein.

1. A leak detection instrument for monitoring gas leakage from a device,comprising: a. an instrument housing; b. a gas sensor supported relativeto said instrument housing and operative upon exposure to a selected gasto generate a corresponding gas detection input signal; c. a gas pumpdisposed within said instrument housing and operative upon actuation todraw the selected gas toward said gas sensor; d. an acoustic emissions(AE) sensor supported relative to said instrument housing and operativeupon exposure to sound attendant with leakage of the selected gas togenerate a corresponding sound detection input signal; e. processingcircuitry for receiving said gas detection input signal and said sounddetection input signal and for producing at least one output signal inresponse thereto; and f. an output device for producing perceptibleoutput in response to said output signal.
 2. A leak detection instrumentaccording to claim 1 wherein said gas sensor is a chemical propertiesleak detector (CPLD).
 3. A leak detection instrument detector accordingto claim 1 wherein said gas sensor is selected from a group consistingof a chemical properties leak detector (CPLD), a thermal conductivitydetector (TCD), a photo-ionization detector (PID), a laserinterferometer (LID), a corona discharge detector (CDD), amicroelectromechanical (MEMS) based detector, a chemical resistor sensor(CRS), and a surface acoustic wave (SAW) detector
 4. (canceled)
 5. Aleak detection instrument according to claim 1 wherein said AE sensor issupported relative to said instrument housing by an AE sensor mountingassembly.
 6. A leak detection instrument according to claim 1 whereinsaid AE sensor is supported relative to said instrument housing by an AEsensor mounting assembly.
 7. A leak detection instrument according toclaim 5 wherein said AE sensor mounting assembly includes an elongatedtubular extension having a proximal end removably attached to saidinstrument housing and extending from said proximal end to terminate ata distal end, and including an AE sensor housing disposed on said distalend.
 8. A leak detection instrument according to claim 7 wherein saidgas sensor is disposed within said instrument housing upstream of saidpump, and wherein said tubular extension is a flexible member definingan airflow passageway between said AE sensor and said gas sensor.
 9. Aleak detection instrument according to claim 8 including a filterinterposed between said AE sensor and said gas sensor.
 10. A leakdetection instrument according to claim 9 including a vacuum switchoperative to monitor said filter and to produce a blocked filterindicator (BFI) signal for processing by said processing circuitry whensaid filter becomes contaminated and its efficacy reduced.
 11. A leakdetection instrument according to claim 8 wherein said pump is operativeupon actuation to draw the target gas from an upstream end of said AEsensor mounting assembly, in a downstream direction along the airflowpassageway, and toward said gas sensor.
 12. A leak detection instrumentaccording to claim 7 wherein said AE sensor is a micro-phonic elementsupported within an interior of said AE sensor housing in electricalcommunication with said processing circuitry.
 13. A leak detectioninstrument according to claim 12 including a plurality of LEDs supportedwithin said AE sensor housing in electrical communication with saidprocessing circuitry.
 14. A leak detection instrument according to claim13 wherein said AE sensor and said LEDs are mounted on a common circuitboard.
 15. A leak detection instrument according to claim 1 wherein saidprocessing circuitry is operative to parallel process said gas detectioninput signal and said sound detection input signal.
 16. A leak detectioninstrument according to claim 1 wherein said processing circuitryincludes at least one processing component selected from a groupconsisting of a microprocessor, a microcontroller and a digital signalprocessor (DSP).
 17. An acoustic emissions (AE) sensor mounting assemblyadapted for connection to a scientific instrument that includes aninstrument housing, processing circuitry for receiving an input sounddetection signal and producing an output signal in response thereto, andan output device for generating perceptible output in response to theoutput signal, said AE sensor mounting assembly comprising: a. amounting member formed as an elongated, tubular extension that isadapted to releaseably connect to the instrument housing, said mountingmember formed to include a gas flow passageway between respective endsthereof; b. an AE sensor housing supported by said mounting member, saidAE sensor housing including a through bore in communication with the gasflow passageway; and c. an AE sensor disposed within said AE sensorhousing and adapted to be placed in electrical communication with saidprocessing circuitry, said AE sensor operative upon exposure to soundattendant with gas leakage from a device to generate the input sounddetection signal for processing.
 18. An AE sensor mounting assemblyaccording to claim 17 wherein said elongated mounting member is aflexible tube having a proximal end releaseably connected to theinstrument housing and extending from said proximal end to terminate ata distal end, said AE sensor housing supported on said distal end. 19.An AE sensor mounting assembly according to claim 17 wherein said AEsensor housing is releaseably connected to said mounting member. 20.(canceled)
 21. An AE sensor mounting assembly according to claim 17wherein said AE sensor housing includes a pair of bored end caps joinedtogether to substantially surround an AE sensor housing interior.
 22. AnAE sensor mounting assembly according to claim 21 wherein a downstreamone of said end caps is removably attached to said mounting member, andwherein an upstream one of said end caps receives said AE sensor.
 23. AnAE sensor mounting assembly according to claim 21 wherein said AE sensoris a micro-phonic element mounted on a circuit board that is supportedwithin the AE sensor housing interior.
 24. An AE sensor mountingassembly according to claim 23 including a plurality of ultraviolet LEDsmounted on said circuit board, said ultraviolet LEDs operative uponemission of ultraviolet light to cause an appropriately dyed target gas,or its residue, in a vicinity of said AE sensor housing to fluoresce.25. An AE sensor mounting assembly according to claim 24 including atleast one photo detector mounted on said circuit board and adapted to beplaced in electrical communication with said processing circuitry, saidphoto detector being responsive to fluorescent light caused by saidemission of ultraviolet light to generate a photo detection signal forprocessing.
 26. An AE sensor mounting assembly according to claim 24wherein said micro-phonic element and said ultraviolet LEDs are mountedon a first surface of said circuit board and project forwardly in anupstream direction, and wherein an upstream one of said end capsincludes a central bore that is directionally aligned with saidmicro-phonic element, and a plurality of radially offset bores eachaxially aligned with a respective one of said ultraviolet LEDs, andincluding at least one visible LED mounted on said circuit board foremitting visible light upon emission of ultraviolet light from saidultraviolet LEDs, thereby to indicate an on state for the ultravioletLEDs.
 27. An AE sensor mounting assembly according to claim 26 includinga plurality of visible LEDs mounted on an opposite second surface ofsaid circuit board and adapted to be placed in electrical communicationwith said processing circuitry, said visible LEDs operative uponemission of visible light to illuminate an area in a vicinity of said AEsensor housing.
 28. An AE sensor mounting assembly according to claim 27wherein said LEDs are equiangularly distributed about said micro-phonicelement.
 29. An AE sensor mounting assembly according to claim 24including a plurality of visible LEDs mounted on said circuit board andadapted to be placed in electrical communication with said processingcircuitry, said visible LEDs operative upon emission of visible light toilluminate an area in a vicinity of said AE sensor housing.
 30. An AEsensor mounting assembly according to claim 29 including a lighttransmissive annular ring sandwiched between said end caps in radialalignment with said visible LEDs.
 31. In a leak detection instrumenthaving an instrument housing, an acoustic emissions (AE) sensorsupported relative to said instrument housing that is operative uponexposure to sound attendant with leakage from a device to produce acorresponding sound detection input signal, AE sensor processingcircuitry disposed within said instrument housing for receiving thesound detection input signal and producing an AE sensor output signal inresponse thereto, and output circuitry for generating associated AEsensor perceptible output in response to said AE sensor output signal,the improvement comprising: a. a gas sensor supported within theinstrument housing, said gas sensor operative upon exposure to aselected gas to generate a corresponding gas detection input signal; b.a pump supported within the instrument housing and operative uponactuation to draw air past said gas sensor; and c. gas sensor processingcircuitry in electrical communication with said gas sensor, said gassensor processing circuitry operative in response to said gas detectioninput signal to generate a corresponding gas detection output signal.32. (canceled)
 33. The improvement according to claim 31 wherein saidoutput circuitry is operative in response to said gas detection outputsignal to generate associated gas sensor perceptible output in responsethereto.
 34. The improvement according to claim 31 wherein said gassensor is selected from a group consisting of a chemical properties leakdetector (CPLD), a thermal conductivity detector (TCD), aphoto-ionization detector (PID), a laser interferometer (LID), a coronadischarge detector (CDD), a microelectromechanical (MEMS) baseddetector, a Chemical Resistor Sensor (CRS), and a surface acoustic wave(SAW) sensor. 35-38. (canceled)
 39. A method of monitoring a device toascertain leakage of a target gas there-from, comprising: a. providing agas sensor that is operative upon exposure to the target gas to generatea corresponding gas detection input signal; b. providing an AE sensorthat is operative upon exposure to airborne sound emanating from thedevice that is attendant with leakage of the target gas to generate acorresponding sound detection input signal; c. visibly illuminating anarea in a vicinity of an upstream location that is in a vicinity of asuspected leak: d. drawing the target gas along a gas flow passagewayfrom the upstream location towards a downstream location whereby thetarget gas encounters said gas sensor and said gas sensor generates saidgas detection input signal; e. exposing said AE sensor to the airbornesound whereby said AE sensor generates said sound detection inputsignal; f. processing said gas detection input signal and said sounddetection input signal to produce at least one output signal in responsethereto; and g. displaying perceptible output in response to said outputsignal.
 40. A method according to claim 39 whereby said sound detectioninput signal and said gas detection input signal are parallel processed.41. (canceled)
 42. (canceled)
 43. A method according to claim 39including illuminating an area in a vicinity of said upstream locationwith ultraviolet light, thereby to cause the target gas or its residueto fluoresce.
 44. A method according to claim 39 including passing thetarget gas through a hydrophilic filter that is interposed between saidgas sensor and said AE sensor.
 45. A method according to claim 44including monitoring said hydrophilic filter in order to produce ablocked filter indication (BFI) signal for processing if efficacy ofsaid filter is reduced below a selected threshold.
 46. A methodaccording to claim 39 whereby said gas detection input signal and saidsound detection input signal are processed by at least one processingcomponent selected from a group consisting of a microprocessor, amicrocontroller and a digital signal processor (DSP).
 47. A method ofmonitoring a device to ascertain leakage of a target gas therefrom,comprising: a. providing a gas sensor that is operative upon exposure tothe target gas to generate a corresponding gas detection input signal;b. providing an AE sensor that is operative upon exposure to airbornesound emanating from the device that is attendant with leakage of thetarget gas to generate a corresponding sound detection input signal; c.passing the target gas through a hydrophilic filter that is interposedbetween said gas sensor and said AE sensor; d. exposing said gas sensorto the target gas whereby said gas sensor generates said gas detectioninput signal; e. exposing said AE sensor to the airborne sound wherebysaid AE sensor generates said sound detection input signal; f.processing said gas detection input signal and said sound detectioninput signal to produce at least one output signal in response thereto;and g. displaying perceptible output in response to said output signal.48. A method according to claim 47 including monitoring said hydrophilicfilter in order to produce a blocked filter indication (BFI) signal forprocessing if efficacy of said filter is reduced below a selectedthreshold.
 49. A method according to claim 47 whereby said gas detectioninput signal and said sound detection input signal are processed by atleast one processing component selected from a group consisting of amicroprocessor, a microcontroller and a digital signal processor (DSP).